XML 57 R46.htm IDEA: XBRL DOCUMENT
v3.24.3

Note 2 - Investments - Schedule of Investments in Unrealized Loss Position (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Less than 12 months, fair value, available for sale securities | $ 17,206 | $ 58,754
Less than 12 months, unrealized loss, available for sale securities | (218) | (637)
12 months or longer, unrealized loss, fair value, available for sale securities | 166,120 | 209,362
12 months or longer, unrealized loss, available for sale securities | (24,294) | (36,064)
Available for sale securities, fair value, total | 183,326 | 268,116
Available for sale securities, unrealized losses total | (24,512) | (36,701)
Less than 12 months, fair value, held to maturity | 0 | 0
Less than 12 months, held to maturity securities | 0 | 0
12 months or longer, unrealized loss, fair value, held to maturity securities | 7,983 | 7,666
12 months or longer, unrealized loss, held to maturity securities | (517) | (834)
Held to maturity securities, fair value, total | 7,983 | 7,666
Held-to-maturity, total | (517) | (834)
Less than 12 months, fair value | 17,206 | 58,754
Less than 12 months, unrealized loss | (218) | (637)
12 months or longer, fair value | 174,103 | 217,028
12 months or longer, unrealized loss | (24,811) | (36,898)
Debt Securities, fair value, total | 191,309 | 275,782
Debt securities, unrealized loss, total | (25,029) | (37,535)
US Government Agencies Debt Securities [Member] |  |
Less than 12 months, fair value, available for sale securities | 0 | 0
Less than 12 months, unrealized loss, available for sale securities | 0 | 0
12 months or longer, unrealized loss, fair value, available for sale securities | 15,653 | 15,972
12 months or longer, unrealized loss, available for sale securities | (2,590) | (3,179)
Available for sale securities, fair value, total | 15,653 | 15,972
Available for sale securities, unrealized losses total | (2,590) | (3,179)
Corporate Debt Securities [Member] |  |
Less than 12 months, fair value, available for sale securities | 3,864 | 959
Less than 12 months, unrealized loss, available for sale securities | (136) | (41)
12 months or longer, unrealized loss, fair value, available for sale securities | 5,400 | 4,300
12 months or longer, unrealized loss, available for sale securities | (600) | (700)
Available for sale securities, fair value, total | 9,264 | 5,259
Available for sale securities, unrealized losses total | (736) | (741)
Less than 12 months, fair value, held to maturity | 0 | 0
Less than 12 months, held to maturity securities | 0 | 0
12 months or longer, unrealized loss, fair value, held to maturity securities | 7,983 | 7,666
12 months or longer, unrealized loss, held to maturity securities | (517) | (834)
Held to maturity securities, fair value, total | 7,983 | 7,666
Held-to-maturity, total | (517) | (834)
Municipal Bonds [Member] |  |
Less than 12 months, fair value, available for sale securities | 44 | 3,922
Less than 12 months, unrealized loss, available for sale securities | 0 | (23)
12 months or longer, unrealized loss, fair value, available for sale securities | 70,584 | 113,577
12 months or longer, unrealized loss, available for sale securities | (10,738) | (19,375)
Available for sale securities, fair value, total | 70,628 | 117,499
Available for sale securities, unrealized losses total | (10,738) | (19,398)
Collateralized Mortgage-Backed Securities [Member] |  |
Less than 12 months, fair value, available for sale securities | 9,492 | 20,662
Less than 12 months, unrealized loss, available for sale securities | (37) | (113)
12 months or longer, unrealized loss, fair value, available for sale securities | 67,032 | 67,376
12 months or longer, unrealized loss, available for sale securities | (9,441) | (11,732)
Available for sale securities, fair value, total | 76,524 | 88,038
Available for sale securities, unrealized losses total | (9,478) | (11,845)
U.S. Small Business Administration Securities [Member] |  |
Less than 12 months, fair value, available for sale securities | 3,806 | 33,211
Less than 12 months, unrealized loss, available for sale securities | (45) | (460)
12 months or longer, unrealized loss, fair value, available for sale securities | 7,451 | 8,137
12 months or longer, unrealized loss, available for sale securities | (925) | (1,078)
Available for sale securities, fair value, total | 11,257 | 41,348
Available for sale securities, unrealized losses total | $ (970) | $ (1,538)

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (available-for-sale and held-to-maturity), in continuous loss position for 12 months or longer. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesAvailableforsaleAndHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (available-for-sale and held-to-maturity), in continuous unrealized loss position for 12 months or longer. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesAvailableforsaleAndHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerFairValue
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Total amount of accumulated unrealized loss on investment in debt security measured at amortized cost (available-for-sale and held-to-maturity), in continuous loss position. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesAvailableforsaleAndHeldtomaturityContinuousUnrealizedLossPositionAccumulatedLossTotal
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Total fair value of investment in debt security measured at amortized cost (available-for-sale and held-to-maturity), in continuous unrealized loss position. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesAvailableforsaleAndHeldtomaturityContinuousUnrealizedLossPositionFairValueTotal
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (available-for-sale and held-to-maturity), in continuous loss position for less than 12 months. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesAvailableforsaleAndHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale and held-to-maturity), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesAvailableforsaleAndHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsFairValue
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss1
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerFairValue1
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss1
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsFairValue1
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesHeldtomaturityUnrealizedLossPositionAccumulatedLoss1
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position. + References No definition available. + Details
Name: | fsbw_DebtSecuritiesHeldtomaturityUnrealizedLossPositionFairValue1
Namespace Prefix: | fsbw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fsbw_USSmallBusinessAdministrationSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |